DOCTORS have used gene therapy to modify the immune systems of 12 patients to help "shield" them from the effects of HIV, the BBC reports.

The new treatment could replace programmes that require HIV patients to take antiretroviral medication every day.

In a study published in the New England Journal of Medicine on Wednesday, scientists said that by creating beneficial mutations in T-cells they might have found a new therapy for improving the health of people with HIV.

Some patients have a rare mutation in their T-cells, white blood cells that are vital to human immune responses, that prevents the virus from getting inside and multiplying.

Doctors working on the study reported that patients receiving their genome-modifying treatment had "decreased viral loads". In one patient who had received the treatment the virus could no longer be detected at all.

Out of the 12 people who took part in the test, six stopped taking their antiretroviral medication so that researchers could assess the effects of the genome-modifying treatment. In four of those patients, the amount of HIV in the blood dropped. And in one patient, the virus could "no longer be detected at all", according to a Massachusetts Institute of Technology (MIT) report.

Doctors stressed that the study was only intended to determine the safety of the treatment, rather than determining whether "HIV shielding" could be a feasible replacement for drug treatment.

"We are absolutely encouraged by these results," said Bruce Levine the director of the Clinical Cell and Vaccine Production Facility at the University of Pennsylvania. "It is an evolution in the treatment of HIV from daily antiretroviral therapy."

Levine, who ran the study with his colleague Carl June, noted that it was too early to say whether the treatment could come to replace daily antiretroviral drugs, The Guardian reports.

"Cure is a four letter word. We don't like to use it, particularly with HIV. We are looking at improving the health and immune function of people with HIV," Levine said.

Academics cautiously welcomed the findings. In an editorial that sat alongside the report, researchers from Stanford and Harvard Universities, Mark Kay and Bruce Walker, wrote: "The tantalising question... is whether it might actually have been partially effective. A definitive answer to this question will require additional studies."